>>82734769 It means that the final determination of virtue, right and wrong cannot come from popular opinion, or from laws and institutions.
If the government is fundamentally unjust, and normal remedies don't work, Captain America would hand has rebelled against the government.
150 years ago, people were stealing private property, violating local, state, and US federal law, attacking law enforcement officers. And I'd bet Captain America would have supported them, given a time travel device plotline.
The underground railroad and abolitionist movement, smuggling people to Canada were extremists, and sometimes quite violent.
And some Klan member can stand by what he thinks is the river of truth all he wants. Cap is still going to punch him in the head if he goes round violating other people's civil rights.